Unreal Engine 3 games on M17x (problems)

Hey guys,

Got my M17x earlier this week. Been installing and running things that were installed on my old machine, and noticed that Unreal Tournament 3, Mirror's Edge and the Nurien demo all run like crap (5 or less FPS in spots, never more than 20-30FPS). I know this wasn't right because my old M1730 ran UT3 solid at 60FPS and Mirror's Edge in the 40-60FPS range. Other games are fine (Crysis, GRID, PhysX Fluid Demo for examples). I spent most of the day yesterday messing around with drivers and configuration and such since I was home sick. Unfortunately, a good portion of the day was thinking there was something wrong with the video drivers or Hybrid/Stealth settings because I had been using ME/UT3 as my benchmarks.

Finally, I noticed that other things were running fine and narrowed it down to UE3 games. After much debugging, I finally noticed that if I set the affinity to a single core, UT3 runs almost fine (ever so slight slowdown in a few spots, I'm sure only because it's a tiny bit choked with only one core).

Has anyone else experienced this? I'm actually pretty sure it was running fine when I initially installed it but only that one evening. The only things I installed after it were Adobe CS4 and Crysis. Don't think I had any Windows updates since then. Basic specs are:

[email protected] (I tried 2.53)
4GB@1066
640GB Raid0
280M SLI
Windows 7 Ultimate (all updates current including DX)

Also, my Vantage score was P11959 (10220/24419). Seems a *little* low, no?